<!doctype html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport"
          content="width=device-width, user-scalable=no, initial-scale=1.0, maximum-scale=1.0, minimum-scale=1.0">
    <meta http-equiv="X-UA-Compatible" content="ie=edge">
    <title>Document</title>
    <style>
        div.dot-loading::after {
            content: '.';
            animation: loading 1s linear infinite; /*  使用一个无限循环的动画来创建一个加载中点点点的效果 */
        }

        @keyframes loading { /* 根据0-100% 不同的时间节点创建不同的content */
            0% {
                content: '.';
            }
            33% {
                content: '..';
            }
            66% {
                content: '...';
            }
        }
    </style>
</head>
<body>
    <div class="dot-loading">加载中</div>
</body>
</html>